The present invention relates to a low dead space easily cleaned manifold for detaching a container of a chemical delivery system, and in particular to an apparatus for delivering high-purity or ultra-high purity chemicals to a use point, such as a semiconductor fabrication facility or tool(s) for chemical deposition. Although the invention may have other applications, it is particularly applicable in semiconductor fabrication.
Semiconductor manufacturers require chemicals having at least a high-purity for production processes to avoid defects in the fabrication of semiconductor devices. The chemicals used in the fabrication of integrated circuits usually must have an ultra-high purity to allow satisfactory process yields. As integrated circuits have decreased in size, there has been an increase in the need to maintain the purity of source chemicals.
One ultra-high purity chemical used in the fabrication of integrated circuits is tetrakis(dimethylamido)titanium (TDMAT). TDMAT is used widely in integrated circuit manufacturing operations, such as chemical vapor deposition (CVD) to form titanium and titanium nitride films, vias and barrier layers.
Integrated circuit fabricators typically require TDMAT with 99.99+% purity, preferably 99.999999+%(8-9""s+%) purity. This high degree of purity is necessary to maintain satisfactory process yields. It also necessitates the use of special equipment to contain and deliver the high-purity or ultra-high purity TDMAT to CVD reaction chambers.
High-purity chemicals and ultra-high purity chemicals, such as TDMAT, are delivered from a bulk chemical delivery system to a use point, such as a semiconductor fabrication facility or tool(s). A delivery system for high-purity chemicals is disclosed in U.S. Pat. No. 5,590,695 (Seigele, et al.) which uses two block valve assemblies 76 and 91, but not to facilitate rapid clean disconnection. (Related patents include U.S. Pat. Nos. 5,465,766; 5,562,132; 5,607,002; 5,711,354; 5,878,793 and 5,964,254.) The system comprises: a block valve assembly housing a low pressure vent valve and a carrier gas isolation valve, while the other block valve assembly houses a container bypass valve and a process isolation canister bypass valve. The block valve assemblies are not in series nor are they used for disconnect of a container from a manifold.
Solvent purging systems for removal of low vapor pressure chemicals from process conduits are disclosed in U.S. Pat. No. 5,964,230 and U.S. Pat. No. 6,138,691. Such systems may add additional complexity to purging and increase the amount of materials which must be disposed of.
Low dead space couplings are known, such as U.S. Pat. No. 6,161,875.
TDMAT is considered a low vapor pressure, high purity chemical by the semiconductor industry, and thus presents special problems when breaking a process line or changing out a process container where the line must be cleaned prior to such detachment. Significant time delays in cleaning down a line or conduit are a disadvantage in the throughput of a wafer processing facility, where expensive tools and large batch processing of expensive wafers, each containing hundreds of integrated circuits require fast processing and avoidance of significant or lengthy offline time for cleaning or changeout of process containers or vessels.
The Present Invention is more specifically directed to the field of process chemical delivery in the electronics industry and other applications requiring low vapor pressure, high purity chemical delivery. More specifically, the present invention is directed to apparatus for the cleaning of process chemical delivery lines, containers and associated apparatus, particularly during changeout of process chemical or process chemical containers in such process chemical delivery lines, quickly and thoroughly, when processing with low vapor pressure, high purity chemicals.
Evacuation and gas purge of process chemical lines have been used to remove residual chemicals from delivery lines. Both vacuum draw and inert gas purge are successful in quickly removing high volatility chemicals, but are not effective with low volatility chemicals. Safety is a problem when extracting highly toxic materials.
Use of solvents to remove residual chemicals has been suggested to remove low vapor pressure chemicals from process lines when the lines need to be disconnected such as for replacement of a vessel or container for either refill or maintenance. However, solvent systems can be complex and require a source of solvent and a means to handle the contaminated solvent after it has been used for its cleaning function.
The present invention overcomes the drawbacks of the prior art in purging and cleaning chemical process lines for low vapor pressure chemicals without the requirements of lengthy purge cycles of pressurized gas and vacuum, as will be more fully set forth below.
The present invention is a purgeable manifold for transfer of low vapor pressure, high purity chemicals in a high purity chemical delivery system, comprising:
(a) a first container for containing a quantity of the low vapor pressure, high purity chemical having at least two ports capable of receiving or dispensing the low vapor pressure, high purity chemical;
(b) a first conduit for detachably connecting the first container to a point of source or dispense of the low vapor pressure, high purity chemical, the first conduit having a first end and a second end and a first low dead space connector for detaching the first end of the first conduit from the second end of the first conduit;
(c) a first block diaphragm valve assembly having first and second diaphragm valves, each diaphragm valve having a diaphragm and having a valve seat side and a diaphragm side, wherein the valve seat side of each diaphragm valve is juxtaposed to the other valve seat side of the other diaphragm valve, and each valve seat side of each diaphragm valve having low vapor pressure, high purity chemical flow communication with the first end of the first conduit, and the diaphragm side of the first diaphragm valve having flow communication with a first of the at least two ports, and the diaphragm side of the second diaphragm valve having flow communication with a conduit capable of a function selected from the group consisting of a source of push gas and a source of vent;
(d) a second block diaphragm valve assembly having third and fourth diaphragm valves, each diaphragm valve having a diaphragm and having a valve seat side and a diaphragm side, wherein the valve seat side of each diaphragm valve is juxtaposed to the other valve seat side of the other diaphragm valve, and each valve seat side of each diaphragm valve having flow communication with the second end of the first conduit, and the diaphragm side of the third diaphragm valve having flow communication with a conduit capable of a function selected from the group consisting of a source of purge gas and vacuum, and the diaphragm side of the fourth diaphragm valve having flow communication with a conduit capable of a function selected from the group consisting of a source of push gas, a source of bubbling gas and a dispense for low vapor pressure, high purity chemical; and
(e) the second port having flow communication with the first container and capable of a function selected from the group consisting of delivering push gas to the first container and dispensing low vapor pressure, high purity chemical in a push gas from the first container.